// 引入 events 模块
let events = require('events');

// 创建 eventEmitter 对象
let eventEmitter = new events.EventEmitter();

// 创建事件处理程序
let connectHandler = function connected() {
    console.log("连接成功");
// 触发 data_received 事件
    eventEmitter.emit("data_received");
}

// 绑定 connection 事件处理程序
eventEmitter.on('connection', connectHandler);

// 使用匿名函数绑定 data_received 事件
eventEmitter.on('data_received', function () {
    console.log("数据接收成功")
});

// 触发 connection 事件
eventEmitter.emit("connection");

console.log("程序执行完毕");